The present invention relates generally to the collection and therapeutic use of body fluids. More specifically, the present invention relates to methods and devices for attempting to substantially reduce or eliminate potential viral contaminants and other pathogens in body fluids, such as blood.
Of course, in a wide variety of therapies, such as transfusions and transplants, body fluids, especially blood components, such as red blood cells, platelets, plasma, and bone marrow, are infused from one or more individuals into a patient. Although such therapies provide treatments, many of which are life saving, and cannot otherwise be provided, due to the transmission of infectious diseases, there may be potential risks to such therapies.
For example, it is known that blood can carry infectious agents, such as hepatitis virus, human immune deficiency virus (an etiological agent for AIDS), cytomegalovirus, Epstein Barr virus, and herpes virus. Although screening methods exist to identify blood that may include such viruses, current screening methods do not assure that every blood unit that contains such a virus is identified.
For example, in this regard, one of the difficulties in testing blood components for viral contamination, such as HIV, is that many current diagnostic tests are based on an identification of antibodies. Therefore, a contaminated blood component will only exhibit a positive test if it includes antibodies for the virus, e.g., anti-HIV. With respect to intracellular viral infections, an individual may not generate antibodies immediately upon infection. Rather, there is a window period that extends from the initial infection of the patient with a virus to the generation of antibodies. When an individual is in this window period, diagnostic tests that are based on antibodies will not identify the individual, or the blood unit, as being infected. But, even though the antibodies are not present, the blood unit can still transmit an infection.
With respect to HIV infection, it is believed that this window period can extend from approximately six weeks up to 48 months. During this time period, an individual who has been infected with HIV and accordingly, whose blood will transmit same, will register a negative antibody response. Currently used screening methods will not identify as contaminated a blood unit from an individual who is infected with HIV, but who has not generated anti-HIV.
In order to address the limitations of current diagnostic techniques and also to deal with the concern of transmission of viral contaminants and other pathogens to a patient receiving a transfusion, recent attention has focussed on the development of viral inactivating agents. It is envisioned that these viral inactivation agents would be added to the body fluid prior to the body fluid being administered to the patient.
For example, a number of photoactive agents that have antiviral action have been explored. These photoactive agents are generally agents that upon activation with light will inactivate or destroy pathogens, e.g., a virus that may be present. Such photoactive agents include: psoralens; porphyrins; phthalocyanines; and dyes, such as methylene blue. See, for example, U.S. Pat. Nos.: 4,748,120; 4,878,891; 5,120,649; and German Patent Application No. DE 39 30 510 A1 (Mohr).
Although such agents provide promise for the treatment of body fluids to eliminate the concern of viral contamination, there may be regulatory, as well as possible other concerns with respect to such agents. Of course, the resultant body fluid to which the anti-viral agent is added will be infused into a patient. Therefore, it is imperative that the agent does not create toxicity issues or other in vivo concerns.
With respect to photoactive agents, a still further issue is that upon activation of the agent and interaction of the agent with a virus, other products may be generated. For example, methylene blue is a photoactive agent that has been shown to have efficacy in inactivating viral contamination in plasma. Although methylene blue has been, through exhaustive testing, shown to have no toxicity concerns, upon photoactivation of methylene blue, photoproducts are generated. Specifically, Azure A and B are generated upon photoactivation of methylene blue. The in vivo effect of these products has not been as well studied as methylene blue in patients and therefore they raise regulatory issues and in vivo concerns.
There therefore is a need for an improved method and system for treating a body fluid to substantially reduce, if not eliminate, viral contaminants that may be present therein.